A developing device includes a developer bearing member, a developer regulating member, and a space ensuring member. The space ensuring member includes a maintaining unit configured to maintain the space between the image bearing member and the developer bearing member, a rotation regulating portion configured to prevent the space ensuring member from moving, and a cover portion disposed to be not in contact with a surface of the developer bearing member and configured to cover a part of the developer bearing member. The cover portion is configured to cover at least part of an area in which the developer bearing member faces the image bearing member in a rotational direction of the developer bearing member, the area being on an outer side than an end portion of the developer regulating member in a longitudinal direction of the developer bearing member.